AP Biology Chapter 3

How do kinks occur in hydrocarbon chains?

A fatty acid has a carboxyl group attached to a long hydrocarbon chain. If there are double bonds between some of the carbons in the chain, the fatty acid is unsaturated and a kink occurs in the chain.

Describe the three components of a nucleotide.

Every nucleotide is comprised of three types of molecules: a pentose (one with five carbons) sugar, a phosphate, and a nitrogen containing base.

Why are fats and oils sometimes called triglycerides?

Because three fatty acids are attached to each glycerol molecule, fats and oils are sometimes called triglycerides. They have many nonpolar C-H bonds, so they do not mix with water.

Explain where fats and oils are produced.

Fats are produced by animals and oils are produced by plants.

Explain why humans cannot utilize the glucose in cellulose as a nutrient source.

Humans have no way to digest cellulose because only microorganisms are able to digest the bond between glucose monomers. For humans, cellulose serves as a dietary fiber which maintains regularity of fecal elimination.

1:2:1

Most carbohydrates have a carbon to hydrogen ratio of 1:2:1. They include single sugar molecules and chains of sugar.

Explain how a polypeptide is constructed from amino acids.

Proteins are polymers constructed from amino acid monomers. The covalent bond between two amino acids is called a peptide bond. A peptide is two or more amino acids bonded together. A polypeptide is a chain of many amino acids joined by peptide bonds.

What is the molecular formula for a simple sugar?

The molecular formula for a simple sugar is some multiple of CH2O, suggesting that every Carbon is bonded to an -H atom and an -OH atom.

Sucrose

sugar used to sweeten foods, the form in which sugar is transported through plants.

organic chemistry

the chemistry of living organisms

inorganic chemistry

the chemistry of nonliving matter

Describe synthesis and degradation.

A cell uses a condensation reaction to synthesize any type of biomolecule (called a dehydration reaction because the equivalent of a water molecule {an -OH and a -H atom} are removed as subunits and joined.) To break down biomolecules, a cell uses a hydrolysis reaction (an -OH group from water attaches to one subunit and an -H from water attaches to the other subunit.)

Compare the four levels of protein structure.

A protein can have up to four levels of structure, called primary, secondary, tertiary, and quaternary.

Explain how ATP is able to store energy.

Adenosine triphosphate is a special nucleotide that stores large amounts of energy needed for various aspects of life.

What is an isomer? A polymer?

An isomer is an organic molecule that has the same molecular formula but different arrangement of atoms (functional groups) as another atom. A polymer is the largest of biomolecules. They are constructed by linking together large numbers of the same type of subunit. (The subunits are called monomers.) A polymer gets longer as monomers bond to each other.

Compare the structure and function of DNA and RNA nucleic acids.

Both DNA and RNA have a pentose sugar, a phosphate (phosphoric acid), and a nitrogen containing base. In DNA, the pentose sugar is deoxyribose while in RNA, it is ribose. DNA lacks an oxygen atom found in RNA. Both contain combinations of four nucleotides, but these differ. In DNA, the pyrimidine bases are cytosine and thymine and the purine bases are adenine and guanine. In RNA, the pyrimidine bases are cytosine and uracil and the purine bases are adenine and guanine. DNA is double stranded, RNA single.

Compare the functions of phospholipids and steroids in cells.

Both phospholipids and steroids contribute to the formation of the plasma membrane. However, steroids are also involved in sex hormones and communication to cells.

Glucose

C6H12O6

Explain how the properties of carbon enable it to produce diverse organic molecules.

Carbon has a total of six electrons, with four on the outer shell. The carbon atom almost always shares electrons with CHNOPS. It can share with as many as four other elements, which makes it an ideal building block for biomolecules. Carbon can bond with other carbon molecules to form a very stable bond which allows for the formation of long carbon chains. Branching of the chain at any carbon atom is possible. In addition to forming single bonds, carbon can form double bonds with itself and other atoms. It can even form triple bonds with itself.

CHNOPS:

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur

Contrast the structures of fats, phospholipids, and steroids.

Fats provide long-term energy storage and insulation in animals. Fats and oils contain two types of subunit molecules: fatty acids and glycerol. *Each fatty acid consists of a long hydrocarbon chain with an even number of carbons and a -COOH (carboxyl) group at one end. * Phospholipids and steroids serve as major components of the plasma membrane in cells. Steroids are involved in cell communication. phospholipid- constructed like a fat except that, instead of a third fatty acid attached to glycerol, there is a polar phosphate group. steroids: lipids that have entirely different structures than fats. Have skeletons of four fused carbon rings, differs by the type of functional group attached to the carbon skeleton.

Discuss what would occur if no water was present during a degradation of a molecule.

If no water was present during the degradation of a molecule nothing would occur and the molecule would remain untouched. In the process of degradation, biomolecules are broken down by adding water to them.

Compare and contrast the structures of cellulose, chitin, and peptidoglycan.

In all three, monomers are connected like cellulose. The cellulose monomer is simply glucose. In chitin, the cellulose monomer has an attached amino group. Peptidoglycan is more complex because each monomer also has an amino acid chain.

Examine which types of amino acids are most likely to be found in the interior of a protein and why.

In the interior of a protein, the nonpolar amino acids tend to group together in order to be as far away from water as possible.

Analyze the factors that affect protein structure and function.

Interaction of hydrophobic amino acids in the polypeptide chain with the surrounding water is the major factor in how proteins fold into and maintain their final shape.

Describe why lipids are essential to living organisms.

Lipids are insoluble in water. Fat is used by animals as insulation and long-term energy storage. Plants use oil for long-term energy storage. Fats are an essential part of diet, providing lots of energy, having twice the caloric density of carbohydrates, and helping to build and maintain cell membranes. They provide padding for internal organs and fuel hormones like estrogen and testosterone.

Evaluate why lipids and water do not mix.

Lipids do not dissolve in water because of their hydrocarbon chains. the hydrogen atoms bonded only to carbon are nonpolar and have no tendency to form hydrogen bonds with water molecules. EX: Nonpolar oil and polar water are not chemically compatible.

Distinguish between a nucleotide and nucleic acid.

Nucleic acids are polymers made up of nucleotides. Nucleic acids include instructions for life, store information, and conduct chemical reactions.

What are nucleotides?

Nucleotides are molecules (like Adenine, Cytosine, Thymine, Guanine) that make up the structural basis of nucleic acids (like DNA {deoxyribonucleic acid} or RNA {ribonucleic acid}).

What are pyrimidines? Purines?

Nucleotides that have a base with a single ring are called pyrimidines and nucleotides with a double ring are called purines.

How can a relatively small number of chemicals be used to build many large, complex, and diverse molecules?

Organic molecules are molecules that contain both carbon and hydrogen. there are four classes of organic compounds: carbohydrates, lipids, proteins, and nucleic acids. These are called the biomolecules and their functions in the cell are diverse. The variety of organic molecules is a result of the unique chemical properties of Carbon.

Explain why phospholipids form a bilayer in water.

Phospholipids have hydrophilic heads and hydrophobic tails. When exposed to water, phospholipids arrange themselves so the polar heads are oriented towards the water and the nonpolar fatty acid tails are oriented away from the water. Phospholipids tend to become bilayers because the polar heads prefer to interact with other polar molecules like water. The bilayer is a key component for keeping cells and the biological compartments within a cell separate.

Describe the functions of proteins in cells.

Proteins are of vital importance to the structure and function of cells. As much as 50% of the dry weight of most cells consist of proteins. They are responsible for metabolism, support, transport, defense, regulation, and movement.

Contrast a saturated fatty acid with an unsaturated fatty acid.

Saturated fatty acids have no double bonds between the carbon atoms and contain as many hydrogen atoms as they can potentially hold. Unsaturated fatty acids have double bonds in the carbon chain, which reduces the number of bonded hydrogen atoms.

Are Saturated fats or Unsaturated fats preferred in diet? Why?

Since saturated fats easily stick together in the blood, unsaturated fats are healthier for diets.

How are organic molecules combined to create structures and functions necessary to support life?

The carbon skeleton, or chain of carbon molecules, accounts for the shape of an organic molecule. A functional group is a specific combination of bonded atoms that always react in the same way, regardless of the particular carbon skeleton. Diversity of organic molecules comes from the attachment of different functional groups to different carbon skeletons.

How does the structure of a polysaccharide aid in the degradation of sugar?

The helical shape of a polysaccharide exposes the sugar linkages to the hydrolytic enzymes that break them down.

List several examples of important monosaccharides and polysaccharides.

The monomer subunits, called monosaccharides, are assembled into long polymer chains called polysaccharides. Monosaccharides consist of only a single sugar molecule and are called simple sugars. Glucose (with 6 carbon atoms) is a hexose sugar critical to biological function, major source of cellular fuel. Is the molecules that is broken down into stored chemical energy or ATP during cellular respiration. Ribose and Deoxyribose (five carbon atoms) pentose sugars that are found in the nucleic acids RNA and DNA. Polysaccharides are polymers of monosaccharides and some function as short-term energy storage molecules. When a polysaccharide breaks down, it releases sugar molecules for energy. Not soluble in water, and larger than simple sugar (so cannot easily pass through the plasma membrane that encloses cells.) starch (plants): store glucose as starch, exists in two forms amylose {nonbranched} and amylopectin {branched}. glycogen (animals):animals store glucose as glycogen. The storage and release of glucose from liver cells is controlled by hormones. (more branched than starch.) Structural polysaccharides include cellulose (plants), chitin (animals and fungi), and peptidoglycan (bacteria).

Why are the pyrimidine and purine bases called "bases"?

The pyrimidine and purine bases are called bases because they raise the pH of a solution.

What promotes the storage of glucose as glycogen?

The release of insulin from the pancreas promotes the storage of glucose as glycogen.

Explain where the information that specifies amino acid sequence in a polypeptide comes from.

The sequence of nucleotides in DNA specifies a complementary sequence of nucleotides in RNA, which in turn, specifies the amino acid sequence of a protein.

Examine why purines and pyrimidines pair together.

The two strand in DNA twist around each other to form a double helix. The strands are held together by the hydrogen bonds between pyrimidine (T and C) and purines (A and G). T is always paired with A and G is always paired with C. The complementary base pairing allows the number of pyrimidines to equal the number of purines despite the order or quantity of any base pair.

Describe how functional groups affect a carbon molecule's chemical reactivity.

When a particular function group is added to a carbon skeleton, the molecule becomes a certain type of compound. Since cells are composed mainly of water, the ability to interact with and be soluble in water profoundly affects the functions of organic molecules. The attached functional groups determine not only the polarity of an organic molecule, but also the types of reactions it will undergo.

Why can one organism use molecules from another organism to build their own?

When an animal digests food, it gets degraded into smaller molecules that are subunits for biomolecules the body uses. the body then takes the subunits (bread- glucose molecules, meat- amino acids) and builds from them the particular carbohydrates and proteins needed to make cells.

Glycerol

a 3 carbon compound with three -OH groups. The -OH groups are polar which makes glycerol soluble in water.

trans-fat

a result of hydrogenation, increases LDL or bad cholesterol and risk of heart attack and coronary heart disease.

functional group

a specific combination of bonded atoms that always react in the same way

quaternary (protein structure)

consist of more than one polypeptide.

Cholesterol

essential component of an animal cell's plasma membrane, provides physical stability.

Lactose

found in milk, glucose combined with galactose.

Chaperone proteins

help new proteins fold into their normal shape, correct any of the "misfolding" of a new protein.

Phospholipids

lipid that contains a phosphate group.

hydrocarbons

long chains of carbon that have additional bonds exclusively with hydrogen atoms. (A hydrocarbon can turn back on itself to form a ring compound when placed in water.) Hydrocarbons are hydrophobic, or not soluble in water.

Waxes

long-chain fatty acids bond with long-chain alcohols. high melting point, hydrophobic

Double bonds

not as flexible as singles, restrict the movement of bonded atoms, change shape and influence function, *one way to distinguish between saturated and unsaturated fats*

tertiary (protein structure)

the folding that results in the final 3D shape of a polypeptide. (Globular proteins- tend to ball up into rounded shapes) Interaction of hydrophobic amino acids in the polypeptide chain with the surrounding water is the major factor in how proteins fold into and maintain their final shape. {when a protein loses its natural shape it is denatured.}

Primary (protein structure)

the sequence of amino acids defined by a gene.

Disaccharide

two monosaccharides that have joined during a dehydration reaction.

What happens when a polysaccharide is branched?

when a polysaccharide is branched, there is no main carbon chain because new chains occur at regular intervals (always the 6th carbon of the monomer.)

Secondary (protein structure)

when the polypeptide coils or folds in a particular way. (coiling alpha helix and pleated beta sheet) {fibrous proteins- which are structural proteins, exist only as helices or pleated sheets that hydrogen bond to each other.}